Development and validation of a pediatric spine surgical invasiveness index.

Purpose: Surgical invasiveness indices have been used in adult spine surgery to characterize the invasiveness of complex procedures and for risk stratification. This has not been studied in the pediatric population. The purpose of this study was to develop and validate a surgical invasiveness index for pediatric spinal deformity surgery.

Methods: The National Surgical Quality Improvement Program (NSQIP) Pediatric database was queried between the years 2016-2022. Patients were included if they were <18 years of age, received posterior or anterior-posterior spinal fusion surgery, and had a diagnosis of spinal deformity. The study cohort was divided into a derivation cohort and a validation cohort. A multivariable linear regression analysis was performed to identify surgical components associated with operative time. Surgical components of interest included number of posterior fusion levels, number of anterior fusion levels, pelvic instrumentation, posterior column osteotomies, three-column osteotomies, and prior spinal deformity surgery. Statistically significant variables were used to establish a pediatric spinal deformity surgical invasiveness index. The score was assessed and validated using linear and logistic regression analysis and receiver operating characteristic curve analysis on operative time and allogeneic transfusion.

Results: There were 37,658 patients included (Derivation cohort: 26,372; Validation cohort: 11,286). In the linear regression analysis, more posterior fusion levels (7-12 levels: 0.54, p<0.001;>12 levels: 1.40, p<0.001), anterior fusion 1-3 levels (2.42, p<0.001), anterior fusion ≥4 levels (2.93, p<0.001), pelvic instrumentation (0.79, p<0.001), and previous spinal deformity surgery (0.44, p<0.001) were associated with longer operative time. Each level of posterior column osteotomy (0.13, p<0.001) and three-column osteotomy (0.61, p<0.001) were associated with increased operative time. Points were assigned to each surgical component: 7-12 posterior fusion levels (4 pts), >12 posterior fusion levels (11 pts), anterior fusion 1-3 levels (19 pts), anterior fusion ≥4 levels (23 pts), pelvic instrumentation (6 pts), previous spinal deformity surgery (3 pts), posterior column osteotomy (1 pt per level), and three-column osteotomy (5 pts per level). In the derivation cohort, each point was associated with an increase in operative time by 0.13 hours (R²=0.16, p<0.001). In the validation cohort, each point was associated with an increase in operative time by 0.12 hours (R²=0.15, p<0.001). In the derivation cohort, the area under the curve (AUC) for operative time ≥8 hours and allogeneic transfusion were 0.74 and 0.71, respectively. In the validation cohort, the AUC for operative time ≥8 hours and allogeneic transfusion were 0.74 and 0.70, respectively.

Conclusion: A pediatric spinal deformity surgical invasiveness index was created and predictive of prolonged operative time and allogeneic transfusion. This is the first quantitative tool to measure the extent of surgical interventions in pediatric spine surgery.